Electron discharge device



April 26, 1932. HOLBORN v ELECTRON DISCHARGE DEVICE Filed Feb. 20, 1924 IN VliN TOR 3. I E Ffederz'clr flolborn NE Y . flashing the device.

Patented Apr. 26, 1932 FREDERICK HOLBORN, I O]? HACKENSACK, JERSEY, ASSIGNOR TO DE FOREST RADIO TELEPHONE &: TELEGRAPH CO, OF JERSEY CITY, NEW JERSEY, A CORPORA- TION OF DELAWARE ELECTRON DISCHARGE DEVICE Application filed February 20, 1924. Serial No. 694,053.

This invention relates to electron discharge devices, and particularly to the method and means for obtaining a reduction of residual gases, generally known as the operation of The objects of this invention are to employ an active substance, that is, a substance which will very readily and freely unite with residual gases in the bulb; to enable use of an alkaline metal to be used, and more specifica-lly to employ sodium as the active substance for flashing; to protect the alkaline metal from the atmosphere until incorporated in the tube and flashed; to provide means for containing the requisite amount of the alkaline metal for each tube; to provide means whereby the alkaline metal may be safely handled and applied; to secure simplicity of construction and operation, and to .obtain other advantages and results as may be brought out in the following description.

' Referring to the accompanying drawings in which like numerals of reference indicate similar parts throughout the several views;

Figure 2 showing a modified manner of obtaining a protected portion of the alkaline metal. y

In the specific embodiment of the invention illustrated in said drawings. the reference numeral 1 indicates any suitable container, such as the retort shown, wherein the alkaline metal, as sodium,may be melted by application of heat or otherwise. In the drawings I have shown heating means 2, and have indicated the melted alkaline metal with numeral 3.

Suitable precaution has to be taken in handling and melting the alkaline metal, and by way of illustration I. have shown the said metal protected by hydrogen which I-prefer using the same at the option of the user of my method, or permitting the gas to escape if such be preferred. y

In order to remove the alkaline metal from the container, I employ a suitable tube 6 which extends practically to the bottom of the container and is connected at its outer end to any suitable pump or suction means. Said tube is preferably of aluminum or other material not acted upon chemically by the par ticular alkaline metal and also of a material not deleterious to an electron discharge device when used therein and the alkaline metal flashed. Aluminum tubing answers the requirements very well. Said tubing is furthermore provided with only a small opening or, bore so it will not hold a great deal of the alkaline metal to fill it.

After the tube 6 is filled, the ends are sealed in any suitable manner as by use of a chemical such as collodion, or by tightly pinching the ends of the tube together. The tube may now be handled freely, and may be severed into short lengths 'or pellets. In order to secure short lengths without affecting the'alkaline metal by exposing it, I prefer to pinch the tubing together where it is intended to sever it, as indicated at 7 in Figure 2, and then cut the tubing where it is pinched together. In

this manner, the atmosphere will not' have a chance to react with the alkaline metal in the of holding is merely illustrative and not to be construedas restrictive of the invention.

Furthermore, I wish it to be. understood that there are other means of manufacturing pellets, as by enclosing an amount of the alkaline metal in a coating of another metal, as tin, tin foil, lead, etc., or-in a chemical coating such as collodion, paraflin, etc., all of which may be done in accordance with my invention by heating the alkaline metal under proper conditions and removing such as is required to make the pellet, protecting the same by the coating before exposing to the atmosphere. As one'means of obtaining a pellet coated with metal, I have shown in Figure 4 a strip 12 with a plurality of holes 13 therein. The strip and holes are of such size and proportions as to enable the alkaline metal to be carried Within the hole when applied as by dipping or otherwise. While the strip is still under the protection of the hydrogen, the metal as tin, lead, aluminum and so forth, or the chemical as collodion, paraffin, etc., may be sprayed or otherwise caused to surround the alkaline metal and protect it. The strip may then be taken out of the hydrogen without detriment and sections thereof cut off and 'used as described above in connection with the tubing.

In use, the pellet applied to the electron discharge plate is heated in any suitable manner to a point where the expansion of the alkaline metal causes the same to force its enclosure open and permits it toimmediately flash or unite with and reduce the residual gases present in the/bulb. .1 Obviously other detail changes and modifications may be made in the manufacture and use of my invention and in the method disclosed for obtaining the structure, and I do not wish to be understood as limiting'myself to the details of the construction or method specifically set forth in this application, except as set forth in the following claims when construed in the light of the prior art.

Having now described my invention, I

claim 1. The method of introducing a chemically active material into an electron dischargedevice which consists in melting sodium in a nonoxidizing atmosphere, drawing the molten sodium into a thin tube, sealing the ends,

of said tube, mounting said sealed tube with-' in the electron discharge device and heating said tube to release the -sodium therefrom said material from the heat ,to which the device is subjected during evacuation and subsisting in enclosing said material in a metal sheath, inserting said sheath in the en velope' and subsequently melting the sheath to liberate tfie material by evaporization.

7. The method of introducing an easily vaporizable material into a container consisting in encasing said material in a less easily vaporizable material, placing said encased material in the container and heating the casing to render the same pervious and to liberate the material therefrom.

8. The method of introducing an extremely chemically active material into an evacuated container consisting in sealing said material in a metal capsule, introducing the capsule into the container and heating the capsule to liberate the material therefrom.

9. The method of introducing sodium into a vacuum device consisting in enclosin said sodium in a metal capsule, placing sai cal sule in the vacuum device and treating t e capsule to liberate the sodium therefrom.

10. A capsule containing an alkali metal composed of a low melting point metal.

11. Themethod-of introducin a chemically active material'into a bulb which consists -in enclosing said material in a protecting sheath of morevrefractory' material, intro-' ducing the material in the bulb while so en-- I closed and subsequently heating the sheath to destroy the same and liberate the material.

12. The method of introducing an extremely chemically active material into a bulb which consists in placing said material in a metal'tube, reducing the size of said tube, severing a ortion of said reduced tubing from the main body thereof, introducing said section into the bulb and liberating the material therefrom.

FREDERICK HOLBORN. 

